RAPAPORT... Gemological Science International (GSI) is urging extra diligence after receiving a lab-grown diamond bearing a treatment generally only found in natural stones.“Diamond-growing technology continues to improve and growers are trying to mimic natural diamonds in every possible way,” GSI chief information officer Nick DelRe said Monday.

The organization’s Mumbai lab identified a synthetic stone that had been drilled into and given an inclusion using High Pressure-High Temperature (HPHT), which was then acid-bleached out.

The remnants of the inclusion strongly resembled laser-drill treatment, which is generally used to remove black inclusions from natural stones to enhance their appearance, but is highly unusual for lab-grown stones, GSI explained. The lab stressed that there was a common misconception in the industry that a diamond can be identified as natural or lab-grown based on inclusions. In this case, an examination that was not thorough could have led to the conclusion that the diamond was natural, because it contained a laser-drill channel.

“There are no recorded cases of lab-grown diamonds with this treatment, nor would it currently make sense to laser-drill these diamonds,” GSI noted. “It is important to use proper processes, equipment and expertise when identifying diamonds.”